I have two M80 and 2 QS8 speaker and a Denon 1908 receiver. The Denon receiver was damaged last month so I am think about to replace it with Marantz SR6006 (it is on sale for $800 now). Anyone know if Marantz receiver has any issue to handle M80 (it is not officially rated for 4 ohm). I mainly listen to classic music and watch movie. I want to have the option to be connect to an external amplifier (like Emotvia XPA5) in the future. Any other recommendations are wellcomed.

Xiao, as always, the absence of an "official" 4ohm rating shouldn't be considered a critical factor. To get such a rating under FTC amplifier regulations the receiver would have to operate into a 4ohm test load at the full rated power for at least five continuous minutes. This is a severe lab test which would never be duplicated in home use. Full power occurs only at brief peaks(if ever)and "4ohm" speakers such as the M80 are around that impedance for less than half their frequency range.

The 6006 should have no difficulties at safe(to your hearing)listening levels and no separate amplifier should be needed.

If you're able to buy from Accessories4less, they have excellent deals on factory refurbished Onkyo, Denon and Marantz units at that price or less.

For what it's worth... I have a Denon 4311CI which does have a 4 ohm option. Even so the amp shut down on big peaks driving the M80s.

Specifically, the new Tron movie. At the beginning where the guy finds his dad's basement setup and is transported to the underworld. There is a big thump sound and that triggered the protection circuit every time (the sound level was up obviously). No such issues with the ADA1000.

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The "4 ohm option" should never be used. It reduces the voltage output of the receiver's power supply section, with a resulting reduction in current and power because of Ohm's Law. This is done as a safety measure to reduce the chance of overheating with low impedance loads, but does so at the expense of maximum performance(lab tests show that maximum power is cut roughly in half). So, the result is directly contrary to "optimizing" the receiver for 4 ohm speakers, which some imagine to be the purpose.

Hmm, that's exactly what I thought the 4 ohm setting would do. The reason I chose 4 ohms was to reduce the possibility of amplifier overload. I realize that this would result in a reduction in output power but my primary concern was to avoid over loading the output stages causing a potential amp failure which could quite possibly damage my woofers via a DC current from a blown power transistor. Man that was a long sentence

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Do you run the M80's full band? Not that it matters now because you have a proper amp to drive them, but with the right source material, peak LFE content is what will usually cause immediate protection shutdown with an inadequate amplifier for the job. Just curious, did you try that scene with the higher ohm setting?

Shutdown, if caused by overheating would be during sustained use over a period of time and would not happen at a repeated single point.

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